Actually it's a limitation on the Apple iOS where it only allows you to download the iOS upgrade file via wi-fi. My understanding is that this is was "by design" since the iOS file is over 100 Mbps which could result to a "billshock" if the person upgrading his iPhone or iPad is on a non-unlimited data plan (which is the case in many markets outside the Philippines). But just to give you a hint... If you have a Globe Supersurf Postpaid Plan on another device (e.g. a Galaxy S3 or another iPhone that allows you to tether via WiFi) you can use that to download the iOS upgrade file.. That was what I did last night using my Samsung Galaxy S3 as a wi-fi hotspot.. to upgrade my iPad mini to iOS 7. by the way back-up your i-device before attempting an iOS upgrade. In comparison, the Android phones (or at least those I have - an S3, a Galaxy Tab 7.7 and a Samsung Note 10.1 allows you to upgrade the Android OS using cellular data.
Hope this helps